A method is disclosed for finding a deformed pattern in an image using a
plurality of sub-patterns. By advantageously restricting sub-pattern
search ranges, search speed is improved, and the incidence of spurious
matches is reduced. The method also quickly decides which sub-pattern
result, of several potential candidates, is most likely to be the correct
match for a deformed sub-pattern. Also, a method is provided for
characterizing a deformed pattern in an image by using results from
feature-based search tools to create a mapping that models the
deformation of the pattern. A transform, selectable by a user, is fit to
the results from the search tools to create a global deformation mapping.
This transformation is fit only to feature points derived from matches
resulting from successful sub-pattern search, without including data from
areas of the pattern that were blank, not matched, or otherwise didn't
contain information about the pattern's distorted location.